Abstract
Global transitions to highly sustainable energy-industry systems imply shifts to high shares of variable renewable energy sources. While onshore solar photovoltaics and wind power can be expected to be the lowest cost electricity sources around the world, land-constrained regions and islands may have limited onshore renewable potential. Thus, offshore energy technologies, including floating solar photovoltaics, offshore wind turbines, and wave power, may become essential. Furthermore, for Hawaiʻi, offshore energy may provide increased supply diversity and avoid land conflicts as electricity generation is expected to increase. The LUT Energy System Transition Model was employed to investigate the techno-economic implications of high technological diversity through integration of offshore energy technologies compared to full cost-optimisation under both self-supply and electricity-based fuel import scenarios. Limiting solar electricity leads to 0–2.3 GW of offshore electricity and 0–4.1 GW of wave power by 2050, but at 3.5–28.0% increased system costs. Under self-supply conditions and an 80% solar photovoltaics limit, a novel interaction between the key offshore technologies was identified with 0.6–1.1 GW of offshore floating photovoltaics, which contribute 12.3% of all electricity generation by 2050. Due to the limited land availability in Hawaiʻi and island regions, ocean energy technologies may significantly contribute to energy-industry system defossilisation.